Variations of physical and chemical properties in relation to erythromycin mycelial dreg dewaterability under heat-activated persulfate oxidation conditioning

Mobile phone-assisted imprinted nanozyme for bicolor colorimetric visual detection of erythromycin in river water and milk samples

The residues of erythromycin (ERY) may have negative impacts on the ecological environment, health, and food safety. How to detect ERY effectively and visually is a challenging issue. Herein, we synthesized a molecularly imprinted polymer based nanozymes for selective detection of erythromycin (ERY-MIPNs) at neutral pH, and developed a mobile phone-assisted bicolor colorimetric detection system. This system produced a wide range of color changes from blue to pinkish purple as the ERY concentration increased, making it easy to capture the visualization result. Also, the system showed good sensitivity to ERY ranging from 15 to 135 μM, with a detection limit of 1.78 μM. In addition, the system worked well in the detection of ERY in river water and milk, with the recoveries of 95.57% ∼ 103.20%. These data suggests that this strategy is of considerable potential for practical applications and it provides a new idea for visual detection with portable measurement.

Enhanced dewatering of activated sludge by acid assisted Heat-CaO2 treatment: Simultaneously removing heavy metals and mitigating antibiotic resistance genes

High water content and accumulation of heavy metals and antibiotic resistance genes (ARGs) in sewage sludge limit its application. Fenton process has been widely used in sludge dewatering, but the use of hydrogen peroxide (H₂O₂) and generation of acid sludge are the main drawbacks. Here, a novel method of heat-CaO₂ treatment was proposed to enhance sludge dewatering. Results showed that CaO₂ (12.5 mg/g dry solids (DS)) combined with heat at 60 °C significantly improved the sludge dewaterability, e.g. the water content decreased from 79.9% to 69.2% and the specific resistance to filtration (SRF) decreased from 9.21 × 10¹³ to 1.51 × 10¹³ m/kg. At 62.5 mg CaO₂/g DS, the final pH of filtrate was close to neutral and the good dewatering performance was still achieved. The improvement of sludge dewaterability was closely correlated with the decomposition of tightly-bound extracellular polymeric substances (EPS), lysis of the sludge cells, and increased particle size of the flocs. The distribution of bacterial community in the sludge has changed, leading to the decreases in the percentage of some ARGs. The concentrations of typical heavy metals wrapped in the sludge colloid network dramatically reduced. Economic analyses showed that the heat-CaO₂ treatment was a promising method for sludge disposal.

Recent trends in advanced oxidation process-based degradation of erythromycin: Pollution status, eco-toxicity and degradation mechanism in aquatic ecosystems

Wide spread documentation of antibiotic pollution is becoming a threat to aquatic environment. Erythromycin (ERY), a macrolide belonging antibiotic is at the top of this list with its concentrations ranging between ng/L to a few μg/L in various global waterbodies giving rise to ERY-resistance genes (ERY-RGs) and ERY- resistance bacteria (ERY-RBs) posing serious threat to the aquatic organisms. ERY seems resistant to various conventional water treatments, remained intact and even increased in terms of mass loads after treatment. Enhanced oxidation potential, wide pH range, elevated selectivity, adaptability and greater efficiency makes advance oxidation processes (AOPs) top priority for degrading pollutants with aromatic rings and unsaturated bonds like ERY. In this manuscript, recent developments in AOPs for ERY degradation are reported along with the factors that affect the degradation mechanism. ERY, marked as a risk prioritized macrolide antibiotic by 2015 released European Union watch list, most probably due to its protein inhibition capability considered third most widely used antibiotic. The current review provides a complete ERY overview including the environmental entry sources, concentration in global waters, ERY status in STPs, as well as factors affecting their functionality. Along with that this study presents complete outlook regarding ERY-RGs and provides an in depth detail regarding ERY's potential threats to aquatic biota. This study helps in figuring out the best possible strategy to tackle antibiotic pollution keeping ERY as a model antibiotic because of extreme toxicity records.

Biodegradation of erythromycin by Delftia lacustris RJJ-61 and characterization of its erythromycin esterase

The residual erythromycin in fermentation waste can pollute the environment and threaten human health. However, there are no effective approaches to remedy this issue. In this study, an erythromycin-degrading bacterium named RJJ-61 was isolated and identified as a strain of Delftia lacustris based on morphological and phylogenetic analyses. The degradation ability of this strain was also evaluated; it could degrade 45.18% of erythromycin at 35°C in 120 h. Furthermore, the key degradation gene ereA was cloned from strain RJJ-61 and expressed in Escherichia coli BL21; the molecular weight of the expressed protein was ~45 kDa. The enzyme activity of EreA was 108.0 mU ml^-1 at 35°C and pH 7.0. Finally, the EreA protein was used to degrade erythromycin from mycelial dregs and 50% diluted solution, and the removal rates in them were 41.42% and 69.78%, respectively. In summary, D. lacustris RJJ-61 is a novel erythromycin-degrading strain that has great potential to remove erythromycin pollutants from the environment.

Investigation on the variations of sludge water holding capacity of electro-dewatering process

Since the effect of electro-dewatering (EDW) on sludge water holding capacity was unknown, tests were conducted in this study to investigate the water holding capacity of EDW sludge and the potential mechanism related to the sludge physicochemical characteristics, EPS properties and sludge structure. Sludge was dewatered to the average moisture content (AMC) of 80%, 70% and 60% with different applied voltages at 20, 30 and 40V in EDW, respectively. Then the dewatered sludge near the anode and cathode were rewatered. The variation of sludge water holding capacity in EDW process was evaluated in terms of filterability and saturated moisture content (SMC), and the filterability was assessed by the specific resistance to filtration (SRF) of rewatered sludge. The results indicated that SRF of rewatered sludge near the cathode increased greatly. The proteins/polysaccharides (PN/PS) of loosely bound extracellular polymeric substances (LB-EPS) was significantly positively correlated with SRF (r = 0.891, p < 0.01). Moreover, the exposure of hydrophobic sites or groups in PN near the cathode improved the surface hydrophobicity of sludge, which reduced the filterability. In addition, higher voltage could destroy the sludge structure near the anode at the later stage of EDW process, leading to the decrease of SRF and SMC. These results expanded the knowledge about changes in sludge properties and water holding capacity during EDW process.

Simultaneous desulfurization and denitrification from flue gas by catalytic ozonation combined with NH3/(NH4)2S2O8 absorption: Mechanisms and recovery of compound fertilizer

An integrated method of simultaneous desulfurization and denitrification from flue gas by catalytic ozonation combined with NH₃/(NH₄)₂S₂O₈ absorption was developed for the first time. It consisted of two parts: (1) the catalytic ozonation of NO over FeO_x/SAPO-34 to study the effects of the various influencing factors, and (2) the absorption-oxidation of NO_x and SO₂ induced by ozone combined with a NH₃/(NH₄)₂S₂O₈ solution in a bubble column reactor. In Part 1, results showed that under the optimal condition of a molar ratio of 0.5 for O₃/NO, a residence time of 3 s, a water vapor volume fraction of 4%, a NO initial concentration of 536 mg/m³, and a SO₂ initial concentration of 343 mg/m³, the oxidation rate of NO was 55%. The characterizations of poisoned catalyst are briefly discussed. In Part 2, as the gas passed sequentially through the ozonizing reactor and the absorber (NH₃/(NH₄)₂S₂O₈ solution of 0.8% ammonia and 0.2 mol/L (NH₄)₂S₂O₈), a NO conversion rate of approximately 92.6% and SO₂ conversion rate of 100% were obtained. The pH of the NH₃/(NH₄)₂S₂O₈ solution had a significant impact on the NO conversion. According to the analysis of the composition of products under different pHs, a mechanism of desulfurization and denitrification based on NH₃/(NH₄)₂S₂O₈ solutions was proposed. The reaction product as a compound fertilizer contained up to 24.5% nitrogen.